172 The American Geologist. September, 1892 
gabbro hills, contains large deposits of titanic magnetite, and 
this ma}' be dismissed with the statement that this ore is at present 
not used, and of little economic concern. This discussion apper- 
tains wholly to the more northern belt where the recent remarkable 
developments have been made. This northern belt embraces non- 
titanic magnetite and hematite as well as limonite and gcethite, or 
"yellow ochre," as it is sometimes denominated by the miners. 
The magnetite thus far discovered is not of economic importance, 
compared with the hematite and gcethite, but there are explora- 
tions now being made in some of the magnetites which promise 
to become perhaps equally valuable with the hematites. 
The non-titanic magnetite is found in the eastern portion of 
the range and at a lower horizon in the strata than the hema- 
tites, and when it is represented in considerable amount there is 
little ox no hematite in commercial quantities. It is sometimes in 
close association with the gabbro containing titanic magnetite, 
and it is a reasonable hypothesis to refer the magnetic quality to 
the effect of the heated gabbro on the original ore, concentrating 
the iron by the expulsion of some of the oxygen. Still there is a 
trace of magnetic ore further west. It is there found in lean 
iron-bearing rock, and occupies belts of a few inches which pass 
through the rock in a rather peculiar zigzag or wandering fashion. 
But still further west the Pewabic quartz3'te, which is the horizon 
which holds the magnetite in the eastern end of the range, is 
again regularly interstratified with magnetite in considerable 
amount, and as such it has been explored for commercial uses. 
Hard hematite is found in the Mesabi range, but it is rather as 
an accidental appendage of the soft hematite, and usually it 
grades into low-grade ore and is discarded. 
Hard limonite is found in larger quantities than hard hematite. 
It is apt to be impure, and it occurs in somewhat the same man- 
ner as the magnetite — i. e. , it branches and permeates a rock bed 
irregularly, though frequently seen in distinct nodules and in 
vugs when it is found to be a valuable ore. 
The hydrated oxide, however, in the form of gcethite is quite 
abundant. Some shipping mines will depend largely on this ore. 
The ore is in the form of ochre-yellow powder, or small masses 
easily reduced to powder. It is found only in the region of the 
recent new developments, in the western portion of the range. 
Soft hematite, however, is the ore for which the "Range" will 
